The heart is the center of a person's circulatory system. It includes an electro-mechanical system performing two major pumping functions. The left portions of the heart draw oxygenated blood from the lungs and pump it to the organs of the body to provide the organs with their metabolic needs for oxygen. The right portions of the heart draw deoxygenated blood from the organs and pump it into the lungs where the blood gets oxygenated. The pumping functions are accomplished by contractions of the myocardium (heart muscles). In a normal heart, the sinoatrial node, the heart's natural pacemaker, generates electrical impulses, known as action potentials, that propagate through an electrical conduction system to various regions of the heart to excite myocardial tissues in these regions. Coordinated delays in the propagations of the action potentials in a normal electrical conduction system cause the various regions of the heart to contract in synchrony such that the pumping functions are performed efficiently.
A blocked or otherwise damaged electrical conduction system causes the myocardium to contract at a rhythm that is too slow, too fast, and/or irregular. Such an abnormal rhythm is generally known as arrhythmia. Arrhythmia reduces the heart's pumping efficiency and hence, diminishes the blood flow to the body. A deteriorated myocardium has decreased contractility, also resulting in diminished blood flow. A heart failure patient usually suffers from both a damaged electrical conduction system and a deteriorated myocardium. The diminished blood flow results in insufficient blood supply to various body organs, preventing these organs to function properly and causing various symptoms.
Various electrical therapies are available to treat cardiac disorders such as various types of arrhythmias and heart failure. These electrical therapies, including pacing and defibrillation therapies, are delivered to various locations of the heart. Various drug therapies are also available to treat cardiac disorders. Some drugs are most efficient or effective when directly applied to the heart, such as to a cardiac region where a disorder originates.
When properly combined, electrical and drug therapies may benefit a patient to an extent beyond what is achievable by either drug therapy or electrical therapy alone. In many circumstances, the electrical and drug therapies are most effective when delivered to specific target regions. Thus, there is a need for a system to perform localized delivery of combined electrical and drug therapies.